Proper 4R Practices Can Lessen Ammonia Toxicity in Roots

Alan Blaylock, Ph.D.

Alan Blaylock, Ph.D.


Senior Agronomist

Dr. Alan Blaylock brings extensive North American and international experience in nutrient management to the agronomy team. University studies and service as a university extension soils specialist prepared him for a long career in the fertilizer industry. Having managed both domestic and global research and education programs, Dr. Blaylock has a wealth of experience in applying science-based nutrient management principles and products to solving practical questions. Dr. Blaylock earned Bachelor of Science and Master of Science degrees in agronomy and horticulture from Brigham Young University and a Ph.D. in soil science from Iowa State University. He has been in agriculture his entire life — from his childhood on an irrigated farm in eastern Oregon to teaching soil science at Iowa State University to his current role as an agronomist at Nutrien. These diverse experiences helped Dr. Blaylock develop the skills to excel in translating complex scientific principles into practical solutions. Although early in his university studies he explored computer science as a profession, deep family roots in agriculture brought him back to the people and values of his heritage. His career satisfaction comes from helping others improve the performance of nutrients and cropping systems.

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Banding nutrients near, below or even in the seed row is a common practice in western dryland cropping systems. However, these placements are a source of risk in stand establishment and seedling root damage. Recent studies at Washington State University by Drs. Isaac Madsen and William Pan have evaluated these risks using a novel and inexpensive imaging technique to assess the rate, source, and placement options when banding nitrogen fertilizers near the seed at planting.

Survival analysis was conducted on canola roots growing into bands of urea, ammonium sulfate (AS) and urea-ammonium nitrate (UAN) and LD50s – lethal dose that results in 50 percent reduction in population – were estimated. Wheat roots were visually assessed for damage when exposed to bands of urea and diammonium phosphate (DAP). In all instances, urea was shown to be the most toxic source of nitrogen. Care should be taken when banding nitrogen fertilizers to account for source and rate in order to prevent root damage. Results of this study were presented at the 2019 Western Nutrient Management Conference. Download the paper here.